Zoology and wildlife conservation

Determination of the Hubble constant from observations of Cepheid variables in the galaxy M96

Article Abstract:

Astronomers calculated the Hubble constant of H(sub o) equal to 69 plus or minus 8 km per second(super -1) per Mpc(super -1), without taking velocity of the clusters as a factor, from data obtained for Cephid variable stars in the galaxy M96. The distance of their host galaxy group, Leo I, which is 11.6 plus or minus 0.8 Mpc, was measured on the basis of the observations. Algorithms were used for identifying the variables. Standard conditions and substantially small corrections in peculiar velocity at star cluster Coma were used for calculating the constant.

A distance to the galaxy NGC4258 from observations of Cepheid variable stars

Article Abstract:

A portion of the nearby galaxy NGC4258 was observed to look for Cepheid variable stars using the WFPC2 camera and the Hubble Space Telescope on 11 epochs in 1998. It was possible to identify and determine light curves, periods, mean magnitudes and colours for 15 Cepheids. The distance calculated from the Cepheids was 8.1 plus or minus 0.4 Mpc. Revising Cepheid-calibrated distance indicators on the basis of the maser distance would boost the measured Hubble constant by 12% plus or minus 9%, with the corresponding age of the Universe falling similarly.

A class of compact dwarf glaxies from disruptive processes in galaxy clusters

Article Abstract:

Results show that the 'ultra-compact' dwarf galaxies are different from both globular star clusters and known dwarf galaxy structurally and dynamically, suggesting a new class of dwarf galaxy. Data point out that these ultra-compact dwarf galaxies are the remnant nuclei of disrupted dwarf galaxies.